<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<body>
	</body>
	<script type="text/javascript">
		//length 是Array的实例属性。返回或设置一个数组中的元素个数
		var arr =["a","b","c"];
		console.log(arr.length,arr);
		
		arr.length = 4;
		console.log(arr.length,arr);
	</script>
</html>
